Satellite wireless communications systems and methods are widely used for wireless communications. Satellite wireless communications systems and methods generally employ at least one space-based component, such as one or more satellites that are configured to wirelessly communicate with a plurality of user equipments (UEs).
A satellite wireless communications system or method may utilize a single antenna beam covering an entire area served by the system. Alternatively, in cellular satellite wireless communications systems and methods, multiple beams are provided, each of which can serve distinct geographical areas in the overall service region, to collectively serve an overall satellite footprint. Thus, a wireless architecture similar to that used in conventional terrestrial wireless systems and methods can be implemented in wireless satellite-based systems and methods. The satellite typically communicates with UEs over a bidirectional communications pathway, with wireless communication signals being communicated from the satellite to the UE over a downlink (DL) or forward link, and from the UE to the satellite over an uplink (UL) or return link. The overall design and operation of wireless systems and methods are well known to those having skill in the art, and need not be described further herein.
Terrestrial networks can enhance satellite system availability, efficiency and/or economic viability by terrestrially reusing at least some of the frequency bands that are allocated to satellite systems. In particular, it is known that it may be difficult for satellite systems to reliably serve densely populated areas, because the satellite signal may be blocked by high-rise structures and/or may not penetrate into buildings. As a result, the satellite spectrum may be underutilized or unutilized in such areas. The terrestrial reuse of at least some of a satellite band's frequencies can reduce or eliminate this potential problem.
Moreover, the capacity of the overall system can be increased significantly by the introduction of terrestrial reuse of a satellite band's frequencies, since terrestrial frequency reuse can be much denser than that of a satellite-only system. In fact, capacity can be enhanced where it may be mostly needed, i.e., densely populated urban/industrial/commercial areas. As a result, the overall system can become much more economically viable, as it may be able to serve a much larger subscriber base.
Aggregate power control may be used when satellite frequencies are reused terrestrially to reduce or prevent radiation by the terrestrial network and the UEs from interfering with the satellite communications. Several examples of aggregate power control have been described in other U.S. Patents.
One example of aggregate power control is described in U.S. Pat. Nos. 7,706,826 and 7,113,778 entitled “Aggregate Radiated Power Control for Multi-band/Multi-mode Satellite Radiotelephone Communications Systems and Methods,” the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein. As described therein, a satellite radiotelephone system includes a space-based component that is configured to communicate with multiple radiotelephones over multiple frequency bands and/or multiple air interfaces. An ancillary terrestrial network is configured to communicate terrestrially with the multiple radiotelephones over substantially the multiple frequency bands and/or substantially the multiple air interfaces. An aggregate radiated power controller is configured to limit an aggregate radiated power by the multiple radiotelephones to a maximum aggregate radiated power. See the common abstract of U.S. Pat. Nos. 7,706,826 and 7,113,778.
Another example of aggregate radiated power control is described in U.S. Pat. No. 7,623,859 entitled “Additional Aggregate Radiated Power Control for Multi-band/Multi-mode Satellite Radiotelephone Communications Systems and Methods,” the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein. As described therein, an Ancillary Terrestrial Network (ATN) includes at least one Ancillary Terrestrial Component (ATC) that is configured to provide wireless communications using frequencies of a satellite frequency band. The ATN provides communications based on a GSM, cdma2000 and/or W-CDMA air interface, under a constrained capacity measure. The capacity measure of the ATN may also be constrained when the ATN provides communications based on an Orthogonal Frequency Division Multiplexed (OFDM) and/or Orthogonal Frequency Division Multiple Access (OFDMA) air interface. Analogous methods of controlling an ATN also may be provided. See the abstract of U.S. Pat. No. 7,623,859.